Electronic displays have a plurality of pixels, which may be settable with a first operating reflection level, a second operating reflection level and an intermediate operating reflection level. Usually, the first level relates to “white”, the second level relates to “black” and the intermediate level relates to “grey”. For example, electronic displays may be based on a per se known electrophoretic material comprising capsules with black and white particles. In order to change image content on an electrophoretic display, new image information is written for a certain amount of time, for example during a period of 300 ms-600 ms. The refresh rate of the active-matrix is usually higher (for example 20 ms frame time for a 50 Hz display and 10 ms frame time for a 100 Hz display). Changing pixels of such display from black to white, for example, requires the pixel capacitors to be charged to a suitable control voltage for 300 ms to 600 ms, in the case where a pulse-width modulation principle is used. During this time the white particles drift towards the top (common) electrode, while the black particles drift towards the bottom electrode, for example an active-matrix back plane. Switching to black requires a control voltage of a different polarity, and applying substantially 0 V on the pixel substantially preserves its condition. Addressing such electrophoretic display for a short time with a certain voltage will result in a situation that a mixture of white and black particles is visible. Because the particles are very small human eyes integrate various ratios of black and white particles to shades/levels of grey. Such condition is regarded as an intermediate reflection level.
Pixels of the known electrophoretic display have a limited bit depth. For example, a 3 bit pixel has 23=8 grey levels. In order to enable 16 levels (distinct shades) the pixels have to be controlled with a 4-bit driving scheme.
For the known electronic display for an equidistant partition of a full dynamic range of a pixel (e.g, between lightest to darkest shades), increasing the bit depth could require increasing the frame rate. Increasing the frame rate generally increases power consumption and potentially leads to a shorter product lifetime. Also, increasing the bit depth requires a higher accuracy and robustness of the method to control the display used to obtain the equidistant partitioning of the dynamic range.